Most Americans can’t pass the civics test required of immigrants.

These days it’s popular to lament that immigrants are destroying America’s national identity, but maybe we’re getting it backward. When the Woodrow Wilson National Fellowship Foundation recently put questions from the U.S. Citizenship Test to American citizens, only one in three could pass the multiple choice test.

It’s embarrassing. According to the foundation, only 13% of Americans knew when the Constitution was ratified, and 60% didn’t know which countries the United States fought in World War II. Most couldn’t correctly...